Atomic punch Astronomers have discovered heavy atoms of ordinary matter in high energy jets being blast out from a feeding black hole.

The finding helps answer a long standing question about the make up of these jets, as well as what causes them to rotate.

Astronomers have been studying black hole jets for many decades, but have been unable to determine what they're made of, or how they reach speed close to the speed of light.

"These are two fairly fundamental problems," says Dr James Miller-Jones of Curtin University in Perth, and co-author of the study published today in the journal Nature.

He says it has been known that the jets contain electrons spiralling around magnetic field lines, giving off radio waves.

Electrons have a negative charge, but astronomers have been unable to detect any overall negative charge in these jets, which Miller-Jones says, indicates they must also contain positively charged particles.

"Until now, it wasn't clear whether the positive charge came from positrons, the antimatter counterpart of electrons, or from positively charged atoms," he says.

Hungry black hole

The team used the Australia Telescope Compact Array and the European Space Agency's XMM-Newton Earth orbiting space telescope, to study radio waves and X-rays emitted by an 'ordinary' black hole, known as 4U1630-47, which was feeding on a companion star.

Miller-Jones and colleagues detected radio emissions coming from the jets the black hole. But, they also found the tell-tale signature of postively charged ions of nickel and iron. The data also indicated the atoms were travelling at about 198,000 kilometres per second, the most accurate measure ever of the speed of jets from a stellar-mass black hole.

"We saw highly ionised iron and nickel atoms, moving fast, at about two thirds the speed of light, and perpendicular to the disk of matter that's whirling around the black hole," says Miller-Jones. "This must be providing the positive charge."

The findings help explain previous studies on the amount of energy flowing out of black holes.

Positively charged atoms are much heavier than the positrons astronomers thought might make up the jets.

"A hydrogen nucleus is about 1800 times the mass of an electron or a positron, while an iron nucleus is 100,000 times more massive," says Miller-Jones. "The jets are much heavier and can carry away more energy from the black hole."

The discovery also suggests that the jets are powered by the black hole's accretion disk - a belt of hot gas swirling around the black hole - and not by the spin of the black hole itself, which would be more likely to produce jets containing only light particles.